The long term effect is that it allows for landlords who own parking spaces to charge what is currently charged for a small apartment, charge for small apartments what is currently changed for large ones, and so on. SF already has a housing problem. This would invite more people in without actually adding proper housing. How many hundreds of thousands or millions of people would do it? Have you thought about the plumbing issues associated with adding people without bathrooms? One person roughing it in a car and using public facilities is ok. Several thousand is an annoyance. Snowball that to few hundred thousand and you have a shit river.